Data Detection and Decoding with Considerations for Channel Estimation Errors Due to Guard Subbands

1. An apparatus comprising: at least one processor configured to derive channel estimates based on received pilot symbols, to derive estimates of channel noise and estimation errors due to at least one pilot subband being zeroed-out so that no pilot transmissions are sent by a transmitter on the at least one zeroed-out pilot subband, wherein deriving the estimates comprises replacing at least one received symbol for the at least one zeroed-out pilot subband with zero, and wherein the at least one processor is also configured to perform data detection on received data symbols with the channel estimates to obtain data symbol estimates, and to compute log likelihood ratios (LLRs) for code bits of each of the received data symbol estimate using the data symbol estimates, the channel estimates and the estimates of the channel noise and estimation errors; and a memory operatively coupled to the at least one processor.

2. The apparatus of claim 1 , wherein the at least one processor is configured to obtain the received pilot symbols from a plurality of pilot subbands uniformly distributed across system bandwidth and including the at least one zeroed-out pilot subband.

3. The apparatus of claim 1 , wherein the at least one processor is configured to derive the channel estimates based on a least-squares channel estimation technique.

4. The apparatus of claim 1 , wherein the at least one processor is configured to derive the channel estimates based on a minimum mean square error (MMSE) technique, a robust MMSE channel estimation technique, or a zero-forcing (ZF) channel estimation technique.

5. The apparatus of claim 1 , wherein the at least one processor is configured to derive channel estimates based on a channel estimation technique, to derive the estimates of the noise and estimation errors based on the channel estimation technique, and to compute the LLRs using the data symbol estimates, the channel estimates and the estimates of the noise and estimation errors.

6. The apparatus of claim 1 , wherein the at least one processor is configured to derive a channel-related part of the noise and estimation errors, to derive a noise-related part of the noise and estimation errors, and to derive the estimates of the noise and estimation errors based on the channel-related part and the noise-related part.

7. The apparatus of claim 1 , wherein the at least one processor is configured to derive a first covariance matrix based on a channel impulse response estimate, to derive a second covariance matrix based on a subband structure used for transmission, to derive a third covariance matrix for the noise and estimation errors based on the first and second covariance matrices, and to compute the LLRs using the third covariance matrix.

8. The apparatus of claim 1 , wherein the at least one processor is configured to perform decoding on the LLRs to obtain decoded data.

9. The apparatus of claim 1 , wherein the at least one processor is configured to perform demodulation for orthogonal frequency division multiplexing (OFDM) to obtain the received pilot symbols for subbands used for pilot transmission and the received data symbols for subbands used for data transmission.

10. The apparatus of claim 1 , wherein the at least one processor is configured to perform demodulation for single-carrier frequency division multiple access (SC-FDMA) to obtain the received pilot symbols for subbands used for pilot transmission and the received data symbols for subbands used for data transmission.

11. A method of processing data, the method comprising: deriving channel estimates based on received pilot symbols; performing data detection on received data symbols with the channel estimates to obtain data symbol estimates; deriving estimates of channel noise and estimation errors due to at least one pilot subband being zeroed-out so that no pilot transmissions are sent by a transmitter on the at least one zeroed-out pilot subband, wherein deriving the estimates comprises replacing at least one received symbol for the at least one zeroed-out pilot subband with zero; and computing log likelihood ratios (LLRs) for code bits of each of the received data symbol estimate using the data symbol estimates, the channel estimates and the estimates of the noise and estimation errors.

12. The method of claim 11 , further comprising: deriving the channel estimates based on a channel estimation technique, wherein the estimates of the noise and estimation errors are derived based on the channel estimation technique, and wherein the LLRs are computed using the data symbol estimates, the channel estimates and the estimates of the noise and estimation errors.

13. An apparatus comprising: means for deriving channel estimates based on received pilot symbols; means for performing data detection on received data symbols with the channel estimates to obtain data symbol estimates; means for deriving estimates of channel noise and estimation errors due to at least one pilot subband being zeroed-out so that no pilot transmissions are sent by a transmitter on the at least one zeroed-out pilot subband, wherein the means for deriving the estimates comprises means for replacing at least one received symbol for the at least one zeroed-out pilot subband with zero; and means for computing log likelihood ratios (LLRs) for code bits of each of the received data symbol estimate using the data symbol estimates, the channel estimates and the estimates of the noise and estimation errors.

14. The apparatus of claim 13 , further comprising: means for deriving channel estimates based on a channel estimation technique, and wherein the means for deriving the estimates of the noise and estimation errors comprises means for deriving the estimates of the noise and estimation errors based on the channel estimation technique, and wherein the means for computing the LLRs comprises means for computing the LLRs using the data symbol estimates, the channel estimates and the estimates of the noise and estimation errors.

15. A non-transitory computer-readable medium for processing data, the non-transitory computer-readable medium having instructions thereon, the instructions comprising: code for deriving channel estimates based on received pilot symbols; code for deriving estimates of channel noise and estimation errors due to at least one pilot subband being zeroed-out so that no pilot transmissions are sent by a transmitter on the at least one zeroed-out pilot subband, wherein the code for deriving the estimates comprises code for replacing at least one received symbol for the at least one zeroed-out pilot subband with zero; and code for computing log likelihood ratios (LLRs) for code bits of each received data symbol estimate using the channel estimates and the estimates of the noise and estimation errors.